1. Field of the Invention
Molding compositions comprising acetal polymers having a high degree of crystallinity at room temperature have been in commercial use for many years. They have application in a wide variety of end uses, e.g., automobile applications such as bumper extensions and instrument panels, plumbing supplies such as valves, shower assemblies, flush tank components, faucets and pipe fittings, tool components such as screw driver adaptors, and household and personal products, such as quick boiling electric water kettles.
These crystalline acetal polymers have a highly favorable spectrum of physical properties which are responsible for their wide commercial acceptance. However, for certain applications, an improved capacity of the latter crystalline polymers for being blended into stable homogeneous molding compositions with other components such as certain stabilizers, would be highly desirable. Moreover, for certain end uses, e.g., those involving a laminated structure or the use of reinforcing materials in the interior of a molded article, a greater degree of adhesiveness between the surface of a crystalline acetal polymer and another surface, e.g., composed also of crystalline acetal polymer, or another material such as glass, metal or wood, is very beneficial.
This invention relates to novel, relatively elastomeric acetal copolymers which have little or no crystallinity at room temperature (about 25.degree. C.). These copolymers have a strong interaction with moldable acetal polymers which contain a major proportion of oxymethylene units in the polymer chain and a high degree of crystallinity at room temperature. Because of this strong interaction, the elastomeric acetal copolymers can be blended with moldable crystalline acetal polymers to obtain a moldable resin composition having improved morphology. The elastomeric acetal copolymers can also be used as bonding resins between two surfaces of a crystalline acetal polymer and between crystalline acetal polymers and other materials such as glass, metal or wood.
2. Description of Related Art
The following prior art references are disclosed in accordance with the terms of 37 CFR 1.56, 1.97 and 1.98.
U.S. Pat. No. 3,639,192, issued Feb. 1, 1972 to Burg et al., discloses for use as adhesives copolymers of formaldehyde or trioxane with 1 to 60% by weight, preferably 1 to 30% by weight, of a cyclic ether, cyclic and/or linear acetal, e.g., 1,3-dioxolane, and/or an alkyl glycidyl formal, polyglycol diglycidyl ether or bis (alkane triol) triformal. Example 5 discloses a terpolymer of 97.95 wt. % of trioxane, 2 wt. % of ethylene oxide, and 0.05 wt. % of 1,4-butanediol diglycidyl ether.
U.S. Pat. No. 3,337,507, issued Aug. 22, 1967 to Gutweiler et al., teaches the formation of high molecular weight copolymers obtained by polymerizing a mixture of trioxane and any of certain polyformals. Example 4 of the patent shows the use of a polyformal which is a clear highly viscous oil at 70.degree. C. obtained by polymerizing a mixture of 1/3 mole of trioxane and 1 mole of dioxolane in the presence of p-nitrophenyl-diazonium fluoroborate as catalyst.
Japanese Kokai Sho 42-22065 of Yamaguchi et al., published Oct. 30, 1967, discloses copolymers of trioxane and an aperiodic ring compound, e.g., 1,3-dioxolane, prepared in liquid sulfur dioxide, and in Example 1 shows a copolymer of trioxane and 64 mol % of 1,3-dioxolane.
Pending application Ser. No. 096,187, filed Sept. 14, 1987 by Collins et al. and now U.S. Pat. No. 4,788,258, issued Nov. 29, 1988, discloses and claims certain copolymers of trioxane with from 65 to 75 mol percent of dioxolane, having an IV of about 1.0 to 2.3, which are useful as blending and adhesive agents for conventional crystalline acetal polymers.
Pending application Ser. No. 096,189 filed Sept. 14, 1987 by Collins et al., discloses and claims bonded articles of conventional crystalline acetal polymers wherein the bonding agents are certain copolymers of trioxane with from 65 to 75 mol percent of dioxolane, having an IV of about 1.0 to 2.3.